Retractable stop assembly

Abstract

A power operated retractable stop assembly includes a body, a drive arm, and a stop arm. The drive arm is pivotable between a pre-locked position and an unlocked position. There is a locked position between the pre-locked position and the unlocked position. The stop arm is pivotally mounted to the body, has a front side for engaging a workpiece, and a back side for engaging the drive arm. When the drive arm is driven to the unlocked position, the drive arm and the stop arm interact to cause the stop arm to follow the drive arm and move to a stop arm released position. This precludes the stop arm from balancing at the stop arm locked position.

1. A power operated retractable stop assembly comprising:
 a body; 
 a reciprocatable member extending into the body and adapted to engage a driving means, the reciprocatable member being driveable between an extended position and a retracted position; 
 a drive arm pivotally mounted to the body and drivingly connected to the reciprocatable member such that the drive arm is pivotable about a drive axis over a motion range between a pre-locked position and an unlocked position in response to movement of the reciprocatable member, the motion range including a locked position between the pre-locked position and the unlocked position, and the drive arm having a central axis passing through the drive axis to define a drive arm plane that pivots with the drive arm; and 
 a stop arm pivotally mounted to the body such that the stop arm is pivotable about a stop axis, the stop arm having a front side for engaging a workpiece and a back side for engaging the drive arm, the stop arm being positioned to apply a reaction force to the drive arm in response to receiving a force exerted on the stop arm front side by a workpiece, 
 wherein the stop arm back side is configured such that the reaction force has a component normal to the drive arm plane when the drive arm is between the pre-locked position and the locked position to urge the drive arm toward the locked position, and such that the reaction force is substantially coplanar with the drive arm plane when the drive arm is in the locked position to cause the drive arm to remain at the locked position with the stop arm held at a stop arm locked position, 
 wherein when the drive arm is driven to the unlocked position, the drive arm and the stop arm interact to cause the stop arm to follow the drive arm and move to a stop arm released position, precluding the stop arm from balancing at the stop arm locked position. 
 
   
   
     2. The stop assembly of  claim 1  wherein the drive arm has an end, and the stop assembly further comprises:
 a cam roller located at the drive arm end and positioned to engage the stop arm back side, the roller having an axis of rotation that is substantially parallel to the drive axis and is substantially coplanar with the drive arm plane. 
 
   
   
     3. The stop assembly of  claim 1  wherein:
 the drive arm has a first end that engages the stop arm back side and a second end, the drive arm having a leg extending toward the drive arm second end; 
 wherein the stop arm has a first end that engages the workpiece and a second end, the stop arm having a leg extending toward the stop arm second end; and 
 wherein when the drive arm is driven to the unlocked position, the stop arm leg rides on the drive arm leg to cause the stop arm to follow the drive arm and move to the stop arm released position. 
 
   
   
     4. The stop assembly of  claim 1  wherein the drive arm and the reciprocating member are configured such that the drive arm pre-locked position corresponds to the reciprocatable member retracted position, and the drive arm unlocked position corresponds to the reciprocatable member extended position. 
   
   
     5. The stop assembly of  claim 1  wherein the drive arm and the reciprocating member are configured such that the drive arm pre-locked position corresponds to the reciprocatable member extended position, and the drive arm unlocked position corresponds to the reciprocatable member retracted position. 
   
   
     6. The stop assembly of  claim 1  further comprising:
 a link connecting the reciprocatable member to the drive arm. 
 
   
   
     7. The stop assembly of  claim 6  wherein the link is reversible to allow the link to connect on either side of the drive arm pivot to accommodate variable driving means mounting capability. 
   
   
     8. The stop assembly of  claim 1  further comprising:
 a piston/cylinder assembly engaging the reciprocatable member for driving the reciprocatable member. 
 
   
   
     9. The stop assembly of  claim 1  further comprising:
 a motor assembly engaging the reciprocatable member for driving the reciprocatable member. 
 
   
   
     10. In a power operated retractable stop assembly including a body, a drive arm, and a stop arm, wherein the drive arm is pivotally mounted to the body and pivotable about a drive axis over a motion range between a pre-locked position and an unlocked position, the motion range including a locked position between the pre-locked position and the unlocked position, and wherein the stop arm is pivotally mounted to the body and pivotable about a stop axis, the stop arm having a front side for engaging a workpiece and a back side for engaging the drive arm, the improvement comprising:
 the drive arm has a first end that engages the stop arm back side and a second end, the drive arm having a leg extending toward the drive arm second end; 
 wherein the stop arm has a first end that engages the workpiece and a second end, the stop arm having a leg extending toward the stop arm second end; and 
 wherein when the drive arm is driven to the unlocked position, the stop arm leg rides on the drive arm leg to cause the stop arm to follow the drive arm and move to a stop arm released position, precluding the stop arm from balancing at a stop arm locked position. 
 
   
   
     11. A method of operating a power operated retractable stop assembly comprising:
 providing a body; 
 providing a reciprocatable member extending into the body and adapted to engage a driving means, the reciprocatable member being driveable between an extended position and a retracted position; 
 providing a drive arm pivotally mounted to the body and drivingly connected to the reciprocatable member such that the drive arm is pivotable about a drive axis over a motion range between a pre-locked position and an unlocked position in response to movement of the reciprocatable member, the motion range including a locked position between the pre-locked position and the unlocked position, and the drive arm having a central axis passing through the drive axis to define a drive arm plane that pivots with the drive arm; and 
 providing a stop arm pivotally mounted to the body such that the stop arm is pivotable about a stop axis, the stop arm having a front side for engaging a workpiece and a back side for engaging the drive arm, the stop arm being positioned to apply a reaction force to the drive arm in response to receiving a force exerted on the stop arm front side by a workpiece, 
 wherein the stop arm back side is configured such that the reaction force has a component normal to the drive arm plane when the drive arm is between the pre-locked position and the locked position to urge the drive arm toward the locked position, and such that the reaction force is substantially coplanar with the drive arm plane when the drive arm is in the locked position to cause the drive arm to remain at the locked position with the stop arm held at a stop arm locked position, 
 wherein when the drive arm is driven to the unlocked position, the drive arm and the stop arm interact to cause the stop arm to follow the drive arm and move to a stop arm released position, precluding the stop arm from balancing at the stop arm locked position.